It is often necessary to repackage flat or curved glass from steel "leanback" glass racks and place the glass sheets into irregularly-shaped wooden crates for shipping. Such wooden crates are often warped and handmade. It is desirable to place such glass sheets into such low cost wooden crates quickly and in a repeatable fashion.
Previous attempts to load such glass sheets into such wooden crates employed known box location assumptions but ignored positional irregularities related to the box bottom or floor. One approach that has been used to detect such positional irregularities is to use a sensor to locate the bottom of the shipping crate.
The U.S. patents to Galvin U.S. Pat. No. 3,168,184; Fujita et al. U.S. Pat. No. 4,884,938; Suda U.S. Pat. No. 5,102,114; and Delventhal et al. U.S. Pat. No. 5,173,029 all disclose automated systems for transporting or repositioning a glass sheet. The Fujita et al. '938 patent in particular discloses a transfer and repositioning device including a three-dimensional movable carriage that incorporates a vacuum holding assembly that is tiltably and fixedly secured to a carriage.
The U.S. patents to Schmidt et al. U.S. Pat. No. 3,630,389; Monforte U.S. Pat. No. 4,627,785; Clark et al. U.S. Pat. No. 4,657,470; No et al. U.S. Pat. No. 4,828,304; Kowaleski et al. U.S. Pat. No. 5,172,922; Kremer U.S. Pat. No. 5,197,847; Konagai U.S. Pat. No. 5,207,553; and French patent Publication No. 2,639,335 all disclose end effector arrangements for use in combination with industrial robots. Each of the end effectors incorporate suction assemblies for holding a work article and many of the end effectors are spring-biased. In particular, the Kowaleski et al. '922 patent discloses a self-aligning vacuum end effector.
The DeFazio U.S. Pat. No. 4,848,757 discloses a compliance device which utilizes coil springs.
However, none of the prior patents noted above deal with a robotic system for repackaging glass panels into irregularity-shaped crates. It is highly desirable to utilize such crates for shipping purposes since such crates are typically very inexpensive compared to steel regularly-shaped crates which are returned for further use due to their costs.